The present invention relates generally to containers and more particularly to plastic containers with threaded closures for containing hazardous materials and the like.
Polyethylene containers are utilized for containing hazardous materials either in free form or as an over packing for metal salvage drums containing hazardous materials. An example of such a container is illustrated in U.S. Pat. No. 4,708,258 issued on Nov. 24, 1987 for SALVAGE DRUM.
This drum-type container is corrosion resistant. Such containers must also have mechanical strength combined with light weight, and they must provide safe containment of hazardous materials without leaking, despite rough handling during transportation.
Such containers must be approved in the United States by the U.S. Department of Transportation (DOT). The rigorous DOT testing requires dropping of a container, generally filled with water, from a specified height onto a concrete slab, and the angle at which the container is dropped onto the concrete is varied for the testing procedure. Such containers are also usually provided in a stackable form so that the containers can be stacked either on top of each other when full or stacked by nesting them into each other when empty. In addition, the lids are usually attached by a threaded connection to provide maximum leak-proof capabilities.
The salvage container described in U.S. Pat. No. 4,708,258 is very effective. However, it is a principal object of the present invention to provide such a container with additional novel improvements which will make such a container even mechanically stronger, more affordable, more suitable for containing hazardous materials in a leak-tight manner and more suitable for manipulating, handling, transporting and storing the containers.
The prior art salvage container described, is specifically designed for spin or rotational molding, instead of blow molding, from a linear low or medium density polyethylene, which inherently makes the container more expensive to manufacture and not as strong as if the container and lid were blow molded of high density/high molecular weight thermoplastic.
In addition, such prior art containers intended for containment of conventional 55 or 95 gallon drums are not provided with a means for securely engaging and confining the salvage drum within the container between the bottom of the container and the underside of the lid when the lid is fully received on the container. In addition, such prior art containers do not provide a secure and easy means for manipulating the containers with a conventional forklift.
It is an object of the present invention to eliminate these disadvantages and thereby provide a blow molded container with a hollow closure therefore which has all of the aforedescribed advantages of more mechanical strength, affordability, suitability for leak-tight containment, and convenience of manipulation for handling and transportation purposes.